Electron tube apparatus



July 5, 1960 R. L. WALTER ETAL ELECTRON TUBE APPARATUS t TETM t L.D w wM mwm s m W u, m 5

Filed June 14, 1955 J m r v ED A r 1 July 5, 1960 R. 1.. WALTER ETAL2,944,187

ELECTRON TUBE APPARATUS Filed June 14, 1955 8 Sheets-Sheet 2 :E II3P/CHARD L. WAL 7'51? (14/1455 C. F/LMEI? EMA/w? H/ESTA ND 35- I IE... aN0 NIH/"0E3 ATTOEA/EV y 1960 R. L. WALTER ET ELECTRON TUBE APPARATUSFiled June 14, 1955 8 SheetsSheet 3 FII I 4:

lQ/CHAED L. WAL 7'67? 2/ JAMES C.-F/L MEE NORMA/V PHIL-STAND INVENTORSJuly 1960 R. 1.. WALTER EI'AL 2,944,187

ELECTRON TUBE APPARATUS Filed June 14, 1955 8 Sheets-Sheet 4 9/ 93 24A/OEMAA/ RH/esrA/w INVENTORS r I E- 5 BY AIIOE/VEV July 5, 1960 R. 1..WALTER ETAL 2,944,187

ELECTRON TUBE APPARATUS Filed June 14, 1955 8 Sheets-Sheet 5 P/CHAED L.WAL. 7'52 52 56 (/aMEs 0. PM M6)? July 5, 1960 R. L. WALTER ETAI-ELECTRON TUBE APPARATUS 8 Sheets-Sheet 6 Filed June 14, 1955 P/CHA 20LW4; 75E dames C. F/LMEIE E Noe/144 /v 9 M65 m/va R. L. WALTER ETAL2,944,187 ELECTRON TUBE. APPARATUS July 5, 1960 8 Sheets-Sheet 7 FiledJune 14, 1955 R505 gm H 22 M 4 5 0 Wm u r M 0 M MW A u, FUN B IIE 1E R.L. WALTER ETA]- ELECTRON TUBE APPARATUS 8 Sheets-Sheet 8 July 5, 1960Filed June 14, 1955 hin [9/0/1450 L. W44 nae dA/wes C. H4452 &

NORMA/VPH/ESTAA/D l/VVf/WOBS ,arranles United States Patent Ofiice2,944,118? Patented July 5, 1960 2,944,187 ELECTRON TUBE APPARATUSRichard L. Walter and James C. Filmer, Palo Alto, and

This invention relates, in general, to electron tube apparatus and, inparticular, to novel electron tube apparatus of the type employingcavity resonators such as, for

example, high power klystro'n tubes utilized in systems found in radar,navigation beacons and linear accelerators, etc. i

i In the art of high frequency amplification, for example,

- that range of frequencies between 2500 and 4000 me.

there has been lacking a pulsed amplifier that would providehigh gain,that is, 55 db or over; high power, that is 1 megawatt or more with anaverage power of 2 kw. at the same time combining reliability and longlife (1000 hours) with ease of operation.

Accordingly, it is the object of this invention to pro vide a novel highpower, high gain, electron tube apparatus offering ease of operation,long life, and electrical stability.

One feature of this invention is a novel cathode electrical socketcomprising a plurality of spring fingers arranged such as to receive andmake electrical contact with a corresponding tube contact therebyfacilitating rapid replacement of tubes.

Another feature of this invention is an output window assembly whichallows the output window to be pressurized and at the same time maintaina good electrical connection under conditions ofexpansion andcontraction of the electrical contact members without the use of hightemperature solders thereby substantially increasing the operating lifeof the tube.

Other features and advantages of this invention will become apparentfrom a perusal of the specifications taktn in connection with theaccompanying drawings wherein,

Fig. 1 is an elevational view partly in sectionshowing the assembledelectron tube apparatus of this invention,

Fig. l-A is an enlarged fragmentary view of a portion of the structureof Fig. 1,

Fig. 2 is a fragmentary side elevation of the structure of Fig. 1, I

Fig. 3 is a fragmentary end view of a cavity resonator and associatedparts,

Fig. 4 is a cross sectional elevational view of the cathode assemblytaken along line 4-4 of Fig. 2,

Fig. 4-A is a fragmentary view of Fig. 4 showing the cathode take-apartjoint, p

i Fig. 5 is an enlarged fragmentary view of the novel cathode buttonsupport. Fig. 6 is an enlarged part sectional view taken along line 66of Fig. 2 looking in the direction of the arrows, 'Fig. 7 is an enlargedcross sectional view taken along line 7+7 of Fig. 2 looking in thedirection of the arrows, Fig. 8 is a fragmentary side view partly insection showing the location of the output window assembly,

- 21 and 22 joined together at their ends.

i Fig. 8,

I assembly taken through Fig. 9 is a sectional view taken along line 9-9of Fig. 10 is a fragmentary view taken along line 1010 of Fig. 9 showingthe electrical contact and pressure seal of the output window assembly,

Fig. 11 is a fragmentary top view of the output window line 11--11 ofFig. 9,

Fig. 12 is a sectional view taken along line 12-12 of Fig. 2 looking inthe direction of the arrows,

Fig. 13 is an end view of the apparatus looking in from the collectorend.

The construction of the novel electron tube apparatus will now bedescribed followed by a description of the operation and function of theapparatus.

Referring now to Fig. l, the novel tube apparatus comprises a cathodestructure 1, resonators 2, 3, 4 and 5 and a collector. assembly 6.Signal energy to be amplified is supplied to the first resonator 2 via aconcentric line input 7 and amplified in successive resonators 3 and 4.The amplified signal is extracted from the output resonator 5 andpropagated to the load through waveguide 8. The cathode is immersed inan oil bath contained within a tank 9 to prevent arc-overs in theexternal cathode region. Surrounding the resonators is an electricalcoil '11 for creating a strong magnetic field to confine the electronbeam in the resonator region.

Referring now to Fig. 4, a source of electrons is supported from andcontained within an evacuated cathode envelope 1?. Comprising thecathode envelope are a plurality of tubular segments 13, 14, 15, 16, 17,18, 19, Of these tubular segments 16, 19 and 22 are of good insulatingmaterial as of glass to allow independent operating potentials to beapplied to certain portions of the cathode assembly. Tubular segments 13and 14 are made of materials having a high magnetic permeability as ofsteel to provide shielding of the cathode from magnetic fields in thecathode vicinity. The cathode envelope is closed at its lower end by abottom cup 23 and at its upward end is securely held by pole piece 24.

.To allow the cathode assembly to be replaced a novel take-apart jointbetween cathode envelope segments 13 and 14 is provided (see Fig. 4-A).At the joint, proper longitudinal alignment of the lower cathodestructure is obtained through the upper horizontal interface. Correcttransverse alignment of the cathode is obtained through the verticalinterface. interposed between these two interfaces is an area ofmutually opposing surfaces which are noncontacting, that is, theopposing faces are spaced apart. These surfaces are spaced apart tocreate a void which destroys the capillary action tending to draw theadhesive substance 25 from its applied region through the horizontalinterface and onto the vertical interface. If the void is not providedadhesive material will contaminate a greater portion of the interfaces.When the lower cathode assembly is then to be replaced, the adhesivematerial sticking to the aligning surfaces must be removed. Oftentimesin cleaning the adhesive from these surfaces the previously acquiredalignment is destroyed. The present novel joint design allows thecathode to be removed, worked on and replaced without expendingunnecessary time in cleaning the joint, meanwhile preserv- 26. Thecathode flange is of heavier construction and serves to strengthen themorefragile cathode envelope. Furthermore cathode flange 26 serves as abumper protector for the glass insulator 16. g

The novel cathode electrical socket is shown in Fig. l-A. Fixedlysecured to'the annular cathode flange 26 and downwardly extendingtherefrom is a tubularcathode electrical contact 27 which engages aplurality of spring type electrical wipers 28 carried upon a cylindricalsupport lead 29 Similarly, a cup-shaped heater contact 31 is secured tothe lower extremity of the cathode envelope throughheater flange .32.and extends downwardly therefrom to. engage. a plurality of heaterwipers 33 carried upon a tubular heatersupply lead 34. As the tube; isinserted into the oil bath the springtype electrical wipers engage.their respective, contacts and because of the spring-tension forcethemselves against the contacting surface. The .leadingiedge ofsaidW-ipers' clean anarea for good electrical contact. Using the" presentdesign it is readily seen that the time required to change at lbe issubstantially reduced.

,T;he,internal1 cathode structure isshown" in detail in Fig. 4.Contained withinathe cathode envelope '12 is preferably a concavecathode emitter 35 having an annular focus ring ,36 positioned slightlyin front of saidv buttonand carried by atubular focusshield 37 which inturn is. supported from the .cathode envelope by focus shield, support39,. Fixedly secured to the cathode focus- 7 ing ring ;3,6 and extendingdownwardly therefrom is; a

novel tubular cathode emitter support 39 (see Fig. haying,slotsrunninglongitudinally thereof thereby creat ing a =plurality.offingers41. Also carried by the focus shield-37 is, an annular double partitionheat shield 42 (Eig- 4);. v

The present novel cathode construction features a cathodeemittersurrounded by a plurality of partitions all serving to retain the heatenergy within the'cathode emitter region therebyvsubstantiallyincreasing thermal efficiency. The cathode emitter support 39 isparticularly unique inthatthe longitudinal slots serve to inhibit heatconductionwhile thefinger portions 41 reflect'jthe heat energy back tothe cathode emitter. It hasfbeen foundthat certain fingers may be cutout to aidin evacnation. of the inner cathode regions withoutsubstantially impairingthermal efficiency. A second embodimentof" thenovel cathode tem'ittersupport 39 has certain fingers bent.outwardlya'short distance to substantially a condi-' tion oficonstant.diameter for those portions of'the tubu lar member, leaving a pluralityof inwardly. convergent fingers to. which. the cathode: emitter isaffixed. This novel design further. prevents heat loss by conductionsince: fewer fingers make contact .with the cathodeemitter. In. allembodiments the cathode emitter 35 is rigidly secured to the extremitiesof certainof the button support fingers. The cathode buttonsupportfeature'is claimed in a copending divisional application, Serial-N0.831,178;

Heating the cathode emitter 35, a double spiral wound filament 43 issupported upon three support rods, long heater lead 44, short heaterlead 45 and center support 46.; Since center support 46: carries nocurrent it is insulated. electrically fromthe-heater filament 43 throughinsulator 47. Extending into the insulator and connecting directly totnefilamenn is heater support 48. Providinglbasesupports for shortheaterlead 45 and filament center support. 46 aretwocircular plates,heater support flange. 49 and getter fiangefil-respectively, saidflangesbeing rigidly secured to the cathode envelope '12. Longheaterlead 44 extends downwardly through noncontactingopenings in heatersupport flange 49 and 'getter flange Sland anchors'on bottomcup 23.

. Referring now to Figs. 2- and'6, a plurality of reentr'ant typecavityresonators 2,- 3, '4 and 5 are' spaced alon g' thick walled cylindricaldrift'tubes 52. spiraling around" the drift tubes is a coolin'g'coil 53through whichis cira 4-, I} culateda coolant "to carry awayheat-"generated in the drift tube vicinity. Encircling and securelyaflixed to the drift tube substantially at either end thereof are twomagnetic pole pieces, cathode pole piece 24 and anode pole piece 54. Aplurality of stiffener plates 55 likewise encircle the drift tube andare Spaced apart in the drift tube midsection. interconnecting the polepieces and stiffener plates are a plurality? of stifiener rods 56 whichare rigidly secured to the stiffening plates as by brazing. It has beenfound that by utilization of the novel stiffener plates and rods themicrophonic tendency of such an electron tube apparatus wassubstantially reduced. Moreover, electrical. talz lzi was? h hmbient temwas greatly enhanced; Because of the magnetic focusing, v not .yet fullydescribed," the-aforementioned magnetic 1 in the cavity re'sonators andextending outwardly thereof through-anaperture in the-resonator wall.Secured to the in wardend of the tuning plunger 57 is a thin rectangular flexible metal di'aphra'gm SS of a good electrical conductingmaterial, for example, copper'plated Monel. The flex ible diaphragmissecured to the cavity resonator wall on two opposite edges only, theremaining two edges being:slightly spaced' from the resonator walls.Interposed -between'the outside wall of the cavity resonator and theoutward extremity of the plunger extension is a bellows 59 whichenvelops the tuning plunger. The

bellows-is sealedatone end to the plunger and at the other *end to theouter- .wall of the cavityresonator thereby maintaining vacuum integritywithin the cavitywhile-at' th'ezsame 'tirne allowing movement of thetuning plunger 51.: 7 h

Secured :to and surrounding the outward" extremity of the tu ningplungeris "a cup shapedtuning rack support 61 having attached to its outwardwall "in diametrically opposedre'lation two smooth rectangular bars,tunin rac'lc support uidesos (Fi'gs;=3' a'nd7). Similarly mountedonrsaidtuning rack support 61 jand ninety degreesto said; g'uides'63 isatoothedban tuning rack 62'. Mounted on the out'wardfside ot-"the cavityend wall' and extending outwardly adjacent the'tuning raek supportguides 63 istuner slide block 64 having two rectangular recesses. fii t.threin 'tfiig'ifl) -a"nd"fitted with bearing liners as of, for example,tetrafluoroethylene[resin to receive the tun ingara'ck suppo'rt"guides63"slidzible therein; 'Actua't'ing" the tuning plunger through co'actionwith tuning rack 62 :isa pinion 65 -rnoui1ted on one extremity of' atuning actuating'rod 66 which extendsthrough-an' opening in andis-heldi'n positionby apinion mount 67; Operating pinion 65 and upwardlyextending through apertures suitably provided in the stiffener-plates=55, actuating rod 66 (Fig. 2) further extendsthrough output pole piece54 and terminals "in a gear case 68 '(Fig: 13-); Within the gear caseand rigidly aflixed to the tuner actuating rod fis a thothed' worm'ear-'69. Interpo'sed between the toothed worm gear and teoutputpolepieceis arectangul'an g'eai casemounting plate-71 (Figs; 7and'3 'having'an aperture therein, the inner surfaceo the apertureform'- ingarearin -shower tiiner'actuatingrodofi; Enveloping the toothedworm gear 6 9f (1'{ig, 13 is the reci' m rff ur-s p 'e i a e W r an pe n72 ide ou ward of the tube f (Fig. 7). 'Rotatable' a worm Shaft} 73positioned to;

. arre rs p rate; with said toothed wormjgeari69 said wortendingfoiitwardly of the gear'case 68 and derivapart at its free endfrom the drift tube ing bearing support from the inner surface of theside opening 72. Remote actuating means may be coupled to the worm shaft73 to effectuate remote tuning of the cavity resonators. Remote tuningis often desirable in variable frequency tubes. When installed in asystem gaining access to the tube may be difficult. Moreover, in somehigh power applications X-ray radiation from the collector can beavoided by tuning from a remote station. Thecavity tuning apparatus,above-described, is claimed in a copending divisional application,Serial No. 831,777.

Output energy (Fig. 8) is extracted from the output cavity resonatorthrough output iris 74. Whence the energy is propagated throughwaveguide 8 outwardly and upwardly through output window 75 (Fig. 9) tothe load. Within said. waveguide.is.a .blocking iris 76 for blockingstray secondary electrons emanating from the collector drift tube. Forevacuation of the tube a pump-out adapter 77 is provided outwardly ofthe blocking iris and protected by an adapter cover 78.

Substantially at the end of waveguide 8 and fixedly secured thereto isthe novel output window assembly comprising a rectangular flange 79bored to receive four bolts 80 (Fig. 8). At the end of said waveguide 8(Figs. 9 and is a second end flange 81 formed to mate with a likerectangular flange portion of a window mounting frame 82 having mountedtherein the output window 75. Encircling the output window frame is apad of good electrical conducting wire mesh 63 of suflicient thicknessto cause a good electrical connection with an enveloping outer segmentof waveguide 84. Said outer segment of waveguide is recessed at itslower end to form a pocket 85 for the wire pad 83 and extends upwardlyof the output window. Rigidly secured to said outer segment of waveguide84 is an output adapter flange 86 suitably bored and tapped to receivethe aforementioned four bolts 80. Interposed between the lower extremityof said outer segment of waveguide 84 and said output window flange 82and encircling said output window flange is a resilient gasket 87 as of,for example, neoprene. To prevent arc-overs and thereby increase thelife of the output window it has been found helpful to pressurize thewaveguide on the outward side of the Window. Because of the widetemperature fluctuations encountered, the output window frameexperiences high expansion and contraction which necessitates the abovenovel arrangement of wire mesh and 0 ring seal, which will provide goodelectrical contact divhile maintaining an adequate seal.

Comprising the magnetic focusing assembly (Fig. 1) an electricalconducting coil 11 wound upon a hollow open-ended cylinder 88 encirclesthe drift tube midsection and is carried between two annular plates 89and 91. The magnetic coil assembly may be rigidly mounted and the tubebody comprising the cathode, cavity, drift tubes and collectorassemblies may be slidably inserted into the center of the magneticcoils. Upper annular plate 89 (see Fig. 7) has a step provided on andencircling its inner circumference which mates with a similar step 92provided on anode pole piece 54 whereby the tube body is suspendedwithin the magnetic coils. Snugly fitting within the lower annular plate91 (Fig. 6) is cathode pole piece 24. Encircling the outer periphery ofcathode pole piece 24 is a recess carrying an O ring 93 of someresilient material, for example, neoprene, to insure that water vaporsfrom the air do not seep through and contaminate the oil bath.

Comprising the collector assembly 6 (Fig. 7) a hollow open-endedcylindrical collector 94 carried by the drift tube 52 is closed at itsupper end by a conical-shaped collector cone 95. Cut into the exteriorof the cylindrical collector 94 is a helical groove thereby creating ahelical land 96. Snugly fitting over the helical land is a hollowopen-ended cylindrical bafiie 97 slightly spaced 52. Carrying the bafile97 is a cylindrical coolant distributor 98 having a conical-shapedinterior enveloping and being slightly spatial relationship and ferentD.C. electrical potentials in use, first and second spaced from thecollector cone 95. Substantially at the upward extremity of the coolantdistributor 98 is an encircling recess 99 serving as a coolantdistributor ring. Carrying the coolant distributor and surrounding thecollector 94 and baflie 97 is a hollow open ended cylindrical coolantjacket 101 secured to the drift tube 52 at the lower end of the saidjacket. Sealed over the outward end of the coolant distributor 98 is acircular plate, collector cap 102 having water passages 103 and 104 cutthereinand fitted with quick disconnect fluid adapter 105.

In operation electronsare emitted from the cathode focused into .a beamby thelfocusing electrode 36 and accelerated through the drift tube'.The signal to be amplified is fed into the inputcavity 2 where the beamis velocity modulated. As, the modulated beam travels down the drifttube it is further modulated by the intermediate bunching cavities 3 and4, while within the drift tube the beam is confined in diameter againstforces tending to spread the beam, such as space charge forces, by themagnetic field lines supplied by the focusing coils 11, said lines offlux being parallel to the drift tube in this region. The output cavityextracts electromagnetic energy from the modulated beam and said energyis then coupled out of the output cavity through iris 74 and propagatedthrough waveguide 8 and window 75 to the load. Tuning of the tube isobtained by a movable wall type tuning plunger which is movable withinthe resonator by rotation of worm shaft 73 which operates upon actuatingrod 66 which in turn cooperates through pinion 65 to cause tuner racksupport and attached plunger and diaphragm to move in and out of thecavity thereby changing the resonant frequency of said cavity.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In an electron tube apparatus an output window assembly comprising awave energy permeable material covering an opening, a flanged frameholding said permeable material, a resilient electrical conductorencircling the outer sides of said frame, a gasket encircling said frameadjacent said flange portion, an outer waveguide enveloping saidresilient electrical conductor, and means for pressing said outerwaveguide snugly against said gasket thereby effecting an air tightelectrical conducting seal between elements which differ greatly intheir eX- pansive characteristics.

2. In a high frequency apparatus, a wave energy permeable materialcovering an opening, a frame holding said permeable material, aresilient electrical conducting Wire mesh contacting said frame, awaveguide contacting said mesh, and sealing means providing a sealbetween said frame and said waveguide thereby effectuating an electricalconducting seal capable of standing high pressures without leakingbetween elements which differ greatly in their expansivecharacteristics.

3. In an electron tube apparatus a cathode electrical socket comprisinga first and second hollow cylindrical conducting receptacle disposed inconcentric overlapping adapted to be operated at difhollow cylindricalelectrical contactor means concentrically disposed in overlappingspatial relationship fixedly carried upon the electron tube and adaptedto make electrical contact with certain electrodes within the cathodeassembly of the electron tube, and spring fingers carried from andoutwardly tensioned of said first and second receptacles whereby whensaid contactors and receptacles are brought together said spring fingerscause a good electrical connection to be made between said receptaclesand said contactors thereby assuring stable and reliable

